chore: smaller docker image, simplification pass on environment variables, fix direct navigation without vite

Dockerfile

@@ -25,9 +25,9 @@ ENV VITE_API_PROTOCOL=$VITE_API_PROTOCOL \
 RUN deno task build
 
 # ── Stage 2: runtime ──────────────────────────────────────────────────────────
-FROM denoland/deno:2.7.11
+FROM denoland/deno:alpine-2.7.11
 
-RUN apt-get update && apt-get install -y --no-install-recommends ffmpeg && rm -rf /var/lib/apt/lists/*
+RUN apk add --no-cache ffmpeg
 
 WORKDIR /app
 
@@ -36,7 +36,6 @@ RUN deno install
 
 COPY api/ ./api/
 COPY --from=builder /app/dist/ ./dist/
-COPY public/ ./public/
 
 # Persistent data: database and uploaded/generated files must be mounted as volumes.
 VOLUME ["/app/api/sql", "/app/api/uploads"]